Participants will be admitted to the NIH Clinical Center for 3 days. They will have blood and urine tests and a heart evaluation, including an echocardiogram-a procedure that uses sound waves to produce images of the heart, and an electrocardiogram-a study of the electrical activity of the heart. When these tests have been completed, patients will take an idebonone capsule. They will be monitored for side effects for 72 hours. Blood samples will be collected through an intravenous catheter (flexible plastic tube placed in a vein) 0.5, 1, 2, 3, 4, 6, 12, 24, 48 and 72 hours after the drug is taken to determine how long it takes for the drug to be eliminated from the body.